Final answer:
The synthesis of mRNA for ribosomal proteins in eukaryotic cells takes place within the nucleus, where it is transcribed and processed, including capping and splicing. This mature mRNA is then exported to the cytoplasm where it guides the synthesis of ribosomal proteins on ribosomes.
Step-by-step explanation:
The synthesis of messenger RNA (mRNA) that encodes the proteins of eukaryotic ribosomes takes place within the nucleus of the cell. Specifically, within the nucleus, there is a specialized region called the nucleolus, which is where ribosomal RNA (rRNA) is synthesized and the initial stages of ribosome assembly occur.
The mRNA for ribosomal proteins is synthesized by RNA polymerase enzymes in the nucleoplasm, then it is processed and transported to the cytoplasm to be used in protein synthesis.
During the process of transcription, pre-mRNAs are first modified with a 5' methylguanosine cap and a poly-A tail to protect against degradation and to facilitate export from the nucleus.
This modification includes the splicing of introns and the joining of exons. Once these mature mRNAs are exported, ribosomal proteins are synthesized in the cytoplasm where ribosomes are located, either free or bound to the endoplasmic reticulum.
It is important to note that while rRNA and tRNA are also produced within the nucleolus and nucleus respectively, it is the mRNA that mainly carries the genetic information from DNA to make ribosomal proteins.
Thus, even though rRNA is a key component of ribosomes, the mRNA that specifically encodes ribosomal proteins is synthesized in the nucleoplasm before undergoing modifications and exportation to the site of protein synthesis.